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| | <categorytree mode=pages>Staphylococcus species</categorytree> | | <categorytree mode=pages>Staphylococcus species</categorytree> |
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| − | ===Overview===
| + | [[Category:Bacterial Organisms]] |
| − | | + | [[Category:Gram_positive_bacteria]] |
| − | *Commensals on skin and mucous membranes of animals and man
| + | [[Category:Cocci]] |
| − | *Enodgenous or exogenous infections
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| − | *Opportunistic pyogenic infections associated with trauma, immusuppression, other infections
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| − | *'''Coagulase-positive''' ''S. aureus'' and ''S. intermedius'' as well as ''S. hyicus'' are important pathogens of animals
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| − | *Fairly stable in environment
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| − | *Strains selective for particular species
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| − | *Cause mastitis, tick pyaemia, exudative epidermitis, botryomycosis and pyoderma
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| − | ===Characteristics===
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| − | *Clusters of Gram-positive cocci
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| − | *At least 30 species
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| − | *Facultative anaerobes
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| − | *Catalase positive, oxidase negative, non-motile
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| − | *Virulent strains are coagulase positive
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| − | *Grow on non-enriched media
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| − | *White or golden colonies
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| − | *''S. aureus'' and ''S. intermedius'' produce double haemolysis; they produce alpha-haemolysin and beta-haemolysin
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| − | *''S. hyicus'' is non-haemolytic
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| − | *Coagulase-negative strains vary in ability to cause haemolysis
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| − | *Slide test to detect bound coagulase (clumping factor) on surface of bacteria; bacteria clump within 1-2 minutes
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| − | *Tube test detects free coagulase, secreted by bactera; positive result indicated by clot formation in tube following 24-hour incubation; free coagulase converts prothrombin to thrombin which converts fibrinogen to fibrin
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| − | *Biochemical tests to differentiate ''S. aureus'' and ''S. intermedius''
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| − | *PCR to differentiate species
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| − | ===Pathogenesis and pathogenicity===
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| − | | |
| − | *Cause suppurative lesions
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| − | *Trauma or immunosuppression predispose to infection
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| − | *Capsular polysaccharide, teichoic acids and potein A prevent opsonisation and therefore phagocytosis
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| − | *Cell wall proteins bind fibronectin and fibrinogen, allowing bacteria to attched to damaged tissues
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| − | *Coagulase, DNase and protein A production mark pathogenicity
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| − | *Haemolysins made by ''S. aureus'' and ''S. intermedius'' act as toxins
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| − | *Alpha-haemolysin prouces a narrow zone of complete haemolysis; this toxin causes necrosis and targets mast cells and plasma cells, whose contents cause damage
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| − | *Beta-haemolysin produces a wide zone of incomplete haemolysis; damages membranes and causes leakage, contributing to necrosis
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| − | *Also gamma and delta toxins
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| − | *Toxic shock syndrome toxin acts as a superantigen, which causes T cell proliferation and production of cytokines, leading to cardiovascular shock, with microthrombus formation in capillaries
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| − | *Enterotoxins produced by some strains of ''S. aureus'' cause food poisoning in humans
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| − | *Proteases, hyaluronidases and lipases facilitate survival of bacteria and spread and tissue destruction
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| − | ===Diagnosis===
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| − | *Clusters of bacteria in Gram-stained smears of pus
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| − | *Culture on selective blood agar and MacConkey agar
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| − | *No growth on MacConkey
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| − | *Colony characteristics, haemolysis, catalase and coagulase production
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| − | *Phage typing for epidemiological studies
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| − | ===Infections in dogs and cats===
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| − | *''S. intermedius'' causes [[Bacterial skin infections - Pathology#Deep pyoderma|deep pyoderma]], otitis externa, mastitis, endometritis, cystitis, osteomyelitis, wound infections, [[Joints Inflammatory - Pathology#In Dogs|dyscospondylitis]]
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| − | *''S. aureus'' may cause gastroenteritis
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| − | ===Coagulase-negative staphylococci===
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| − | *Usually harmless commensals or secondary invaders
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| − | *May adhere to indwelling catheters leading to urinary tract infections
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| − | *Often display multiple antibiotic resistance
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| − | | |
| − | ==Enteritis==
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| − | * 30% strains of ''[[Staphylococcus aureus]]'' produce potent enterotoxin. T
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| − | ** Protein and heat-stable
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| − | ** Responsible for staphylococcal food poisoning in man.
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| − | * Every reason to assume that acute gastro-intestinal disturbance in small animals may be caused by these enterotoxins BUT not well documented.
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| − | * Symptoms last 24-36 hours and include:
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| − | ** Acute vomiting
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| − | ** Diarrhoea
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| − | ** Pain
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| − | * The enterotoxins are superantigens.
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| − | ** Induce release of cytokines from lymphocytes
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| − | [[Category:Bacteria]][[Category:Gram_positive_bacteria]][[Category:Cocci]]
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| | [[Category:Enteritis,_Bacterial]] | | [[Category:Enteritis,_Bacterial]] |